This protocol describes an approach to the questions of whether bioequivalence of two generic and a standard verapamil product in one population is also demonstrable in another population. The study is to assess the relative proportion of verapamil isomers in each formulation in vitro and in vivo concentration of the isomers after administration of each formulation to young and elderly subjects, to compare intrasubject variability through duplicate drug administration for the three products to be assessed.